Why Do Users Still Set a ‘Max Fee’ Even with a Dynamic ‘Base Fee’?

The Max Fee is the absolute maximum amount a user is willing to pay per unit of gas, encompassing both the Base Fee and the Priority Fee. Since the Base Fee is dynamic and can spike rapidly during congestion, the Max Fee acts as a safety cap to prevent unexpectedly high transaction costs.

Any difference between the Max Fee and the sum of the Base Fee and Priority Fee is refunded to the user.